The present invention concerns a device for driving a gripper belt which has a three-dimensional cam drive for converting a rotational movement into a swinging movement with a cam carrier that executes a rotational movement and with a pivot arm that engages the cam carrier and executes the swinging movement. The invention also concerns a loom having such a device.
It is known to convert the rotational movement of the drive shaft of a rapier loom into a reciprocating movement for a gripper belt wheel with the help of a crank arm having a cardan joint or with the help of a three-dimensional cam drive.
Three-dimensional cam drives provided for this purpose employ a rotating cam carrier which is engaged by a pivot arm which generates the desired swinging movement.
Grooved cam globoids or hyperboloids are suitable curve carriers, but in practice, for manufacturing reasons, they are formed as cylindrical curves.
Such cam drives have the disadvantage that the pivot angle is limited. To compensate for this disadvantage, the diameter of the cam cylinder is made correspondingly large and the length of the pivot arm is increased. This leads to other disadvantages; namely, large masses and a limited stroke.